One—step RT—PCR was used to detect papaya ringspot virus(PRSV)movement in susceptible and resistant(mutant)papaya(Carla papaya L )plants．The time of post—inoculation at which PRSV Wc-lS first detected in susceptible plants was 48 hours in the other area of inoculated leaves OUt Of inoculated sites．4 days in the petioles of inoculated leaf and 6 days in all parts of plant．Compa rative— ly，in resistant plants，the inoculated sites were the only area at which PRSV can be detected any time．Therefore．it was proposed that the mutated resistance to PRSV protects the virus from moving out of inoculated sites or／and into non- noculated areas．